Control is by the machines front panel, a hand held remote control which emulates the front panel or a serial port for computer control. The machine can play forwards (or backwards) from still to 20 times normal speed and also perform other functions such as playing a pre-programmed sequence of frames. The maximum frame to frame seek time is approximately one half second.
The LVR was originally directly connected to the LIVE-NET computer which was in the same room. It is now located separately but is still controlled by the same machine using a connection on the Internet.
A control program was written for the LVR which can emulate the front panel of the machine or act as a sophisticated slide viewer capable of displaying still frames or moving video clips. The slide viewer works by reading a previously prepared file which lists the numbers of the frames to be displayed. Each entry is either a single frame number for still pictures or two frame numbers (the start and stop points) for a video clip. Since the LVR is essentially a random access device the entries in the file do not have to be in the same order as the actual frames on the disc.
There is also a keyword retrieval program which can locate and display the frames that match an arbitrary boolean expression based on a description of the frames held in a database. The time taken to locate and display the first frame is less than the seek time of the LVR.
The LVR has been used during satellite broadcasts, lectures and research. During satellite broadcasts the LVR is used to produce a countdown timer to mark the start and end of the transmission and display pictures of people who participate by telephone (ie. audio only).
When a lecturer wanted to use the LVR they would record the images they wanted on the machine several days before. During the lecture they would select the image they wanted to display using the control program and switch between the lecturers camera and the LVR with a video switch box.
Whilst it would have been possible for lecturers to show slides using a slide video converter or illustrations with an overhead camera without using the LVR it was much more convenient being able to prepare illustrations beforehand, especially when there were a large number, since it eliminated the time taken in setting up the material and they could be reused if a lecture was repeated.
Graphics Multimedia Virtual Environments Visualisation Contents